Drs. Jack U'Ren, Paul Haydock and Sharon Howard (Saigene Corporation [formally the Diagnostic Division of the MicroProbe Corporation], Bothell, WA) propose to develop a low cost HIV drug-resistant monitoring assay. This product will both rapidly quantify viral load and identify mutations in the HIV reverse transcriptase gene. At present, no products exist which measure both viral load and identify drug-resistant mutations at the same time from the same sample. The overall aim will be accomplished by performing quantitative PCR followed by examining probe binding at known mutant locations within the HIV RT gene. In phase I, the assay will develop be developed by focusing on PCR conditions, primers, capture sequences, and internal standards which quantitatively detect wild type and drug- resistant HIV. The developed assay will then be evaluated using characterized drug-resistant HIV strains. In Phase II, the assay will be expanded to other drugs and drug combinations, and will employ clinical samples. These results will be compared to more costly DNA sequencing methods in ongoing clinical studies. The ultimate clinical application will be to provide drug resistance information for patient management, such that knowing the precise nature of a drug resistant mutation may predict cross-resistance or reduced resistance to other drugs.